As shown in FIG. 1, for example, a conventional turret punch press includes an upper turret 96 and a lower turret 97. A punch P is mounted on the upper turret 96 through a punch holder 94. A die D is mounted on the lower turret 97 through a die holder 95.
With this structure, when a striker (not shown) strikes the punch P, the punch P goes down, and the punch P punches a workpiece W grasped by a clamp 93 in cooperation with the die D.
A punched-out or die-cut scrap W1 produced by punching the workpiece W naturally drops into a scrap discharge hole 90 and is collected in a scrap bucket provided in the turret punch press.
After the punching operation, the punch P rises and returns to its original position.
However, the scrap W1 (FIG. 1) produced by punching the workpiece W sticks on a tip end of the punch P, and when the punch P rises, the scrap W1 also floats and sticks on an upper surface of the workpiece W in some cases.
As a result, the workpiece W is damaged and this deteriorates quality thereof.
Japanese Utility Model Publication No. S52-50475 (FIG. 2) and Japanese Patent Application Laid-open No. 2000-51966 (FIG. 3) disclose mechanisms for preventing such scrap floating.
In these conventional techniques, an air jet hole 91 (FIG. 2), 92 (FIG. 3) connected to an air source is downwardly inclined through a predetermined angle θ.
This structure can be applied to a punch press, but cannot be applied to a turret punch press which has a plurality of metal molds disposed on a rotatably turret and which rotation-indexes the metal molds, thereby selecting a desired one of the metal molds and carrying out the punching operation. However, the scrap floating prevention mechanism shown in each of FIGS. 2 and 3 has a single fixed metal mold.
FIGS. 4 to 12 show scrap floating prevention mechanisms applied to a turret punch press.
Among the scrap floating prevention mechanisms, in the scrap floating prevention mechanism shown in FIGS. 4 to 7, a stroke amount H of the punch P is increased (FIGS. 4 and 5), the punch P is provided at its tip end with a scrap pusher 98 (FIG. 6), or by forming the tip end of the punch P with oblique angle (FIG. 7), the scrap W1 is forcibly dropped, thereby preventing the scrap floating.
According to the scrap floating prevention mechanism shown in FIGS. 8 to 12, the roughness of an inner surface of the die D is increased (FIG. 8), the inner surface of the die D is formed with a groove (FIGS. 9 and 10), the inner surface of the die D is formed with a projection (FIG. 11), or a straight portion of a blade of the die D is shortened (by an amount h shown in FIG. 12, for example) to make the die D thin, the friction force between the die D and the scrap W1 is increased so that the scrap W1 does not float together with the punch P, thereby preventing the scrap floating.
However, in the case of the scrap floating prevention mechanism obtained by devising the metal molds P and D shown in FIGS. 4 to 12, the mechanism is limited to the size of the metal mold, and the mechanism cannot easily be applied to a small metal mold in some cases. Further, since the metal molds P and D is subjected to additional work or the metal mold is formed into special shape, the mechanism cannot be applied to a standard metal mold, and a special metal mold is required. As a result, the cost is increased.
In another mechanism for preventing the scrap floating, there is one in which a tip end of the punch P is provided with a scrap pusher, or air is utilized (for example, Japanese Patent Application No. 2002-166876).
According to such a scrap floating prevention mechanism, however, when the metal mold has a large bore and a thin blade in which sizes of a cutting edge of the punch P and a cutting edge of a die hole corresponding to the former cutting edge are 5 mm×40 mm, only little effect is exhibited.
That is, when a metal mold has a large bore and a thin blade, the width of the punch P is small and it is difficult to provide a scrap pusher.
In a scrap floating prevention mechanism utilizing air, the die D is placed on an ejector pipe or a nozzle member, and a side surface of the ejector pipe or the nozzle member is provided with a plurality of air injecting ports.
Therefore, when vertical positions of the air injecting ports are located away from the die holes for punching the workpiece W and when the metal mold has a large bore and a thin blade, the ejector pipe and the nozzle member also become large bores. Therefore, lateral positions of the air injecting ports are separated from a central portion.
As a result, a negative pressure generating position is far from the die hole and the generated negative pressure itself is small and thus, an amount of outside air sucked from the die hole is reduced, and air suction force becomes small. Therefore, a large scrap W1 (for example, 5 mm×40 mm) generated when the workpiece W is punched cannot be discharged.
The scrap floating prevention mechanism utilizing air is formed with an extremely wide scrap discharge hole below the die D. Thus, outside air sucked from the die hole is dispersed in this wide scrap discharge hole, and the sucking effect is small.
In the scrap floating prevention mechanism using air explained in the above conventional example (Japanese Patent Application No. 2002-166876), a die holder 95 on which the die D is mounted is fixed, and this mechanism cannot be applied to a rotatable die holder.
That is, as is well known, the punch holder 94 and the die holder 95 are mounted on a rotatably punch receiver and a rotatable die receiver, respectively, predetermined punch P and die D whose punching shapes have directivity are positioned on a punching center and then, the punch P and the die D are rotated through predetermined angles and the workpiece W is punched in some cases.
In a turret punch press having such a metal mold rotation mechanism, however, air for preventing scrap floating cannot be supplied in the conventional technique. Thus, a scrap W1 generated during the punching operation cannot be discharged and as a result, an application range of the scrap floating prevention mechanism using air is narrowed.
In other words, the conventional scrap floating prevention mechanism using air can be applied only to a case where the metal molds P and D is fixed, and when the metal molds P and D can rotate, the scrap floating prevention mechanism cannot be applied.
The present invention has been achieved in order to solve the above problems, and it is a first object of the invention to provide a scrap floating prevention mechanism, a die apparatus, a die, and a nozzle member which can be applied to a punch press, and to a metal mold having a large bore, a small metal mold, and a metal mold having a rotation mechanism.
It is a second object of the invention to provide a die apparatus, a die, and a nozzle member having a scrap floating prevention mechanism which can be applied to a metal mold having a thin blade.
It is a third object of the invention to provide a scrap floating prevention mechanism which can be applied to a rotating metal mold by making it possible to supply air in a punch P having a metal mold rotation mechanism even when the metal mold is positioned with any angle.